Talk:Chromatography

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Question[edit]

I am not sure if this is the correct place to ask, however.. Can someone please explain to me the difference between affinity, ion exchange etc and high pressure liquid chromatography. Is it as simple as a different matrix and the sample being applied under high pressure?

I am not sure if many people are following this discussion, but here goes. Is the picture located at the beginning of this article a good representation of a typical chromatographic system? It is certainly unique but does it help the novice interested in learning chromatography?Rob.OBrien (talk) 05:05, 9 September 2009 (UTC)

This page needs a lot of more details[edit]

This page needs a lot of more details, what the procedures for the columns are, and the pros and cons to make a decision when to use which one. massa 16:10, 14 Nov 2004 (UTC)

I am teaching an upper level undergraduate course and graduate course in Chromatography and Mass Spectrometry. Over the years I have not found a suitable textbook and so I am considering using primary resources and these WikiPages as reference points. My students will also be challenged to edit and clarify these pages when possible. If we had other academics do the same thing then this could be a good way to improve the material. '''''R.O'B''''' at UBC Okanagan (talk) 13:53, 20 December 2007 (UTC)RobOBrien

I AM WORKING IN A REFINERY'S CHEMICAL LABORATORY IN NE INDIA, I WANT TO KNOW ABOUT HIGH PERFORMANCE LIQUID CHROMOTOGRAPHY.HOW IT IS OPERATED ? PLZ LET ME KNOW ABOUT THIS. —Preceding unsigned comment added by 117.198.54.70 (talk) 15:17, 25 December 2008 (UTC)

Chromabarography[edit]

This was included in the article by User:Invent, the content needs to be verified, a search for chromabarography on the Web of Science gives no results. Could be a hoax

Chromatography is nothing else than the mirror of analytical chemistry. What do you think, what does the analytical instrumentation-making expect in the near future?
Truly - a new technology!
XXI century puts the task for the qualitative improvement of the possibilities of the chromatographic apparatus. One of them is the new technology of Chromatography - Chromabarography. In the development of chromatography, a process that goes on up to day, a definite tendency is traced. After the substantial theoretical and technological "gush" it follows to provide the equipment with additional parts allowing the enlargement of the analytical possibilities of the chromatograph. On this background it is considered in-time to develop such a rich with its possibilities and effective technology a gas chromatography as Chromabarography - a new basic technology of chromatography.
What does it present itself, what does it give to the user and producer of the equipment?
After all, the heart of chromatography is the chromatographic column. The theory of gas chromatography, presented by the equation of Van Deemter, shows that for each chromatographic separation there exists an optimal flow rate above and below which the column efficiency is reduced. In practice, the linear speed of the sample zone moved by the carrier gas, is changed continuously and increases as it approaches the outlet, which results in a non-effective use of a part of the column. In this case equation characterizes the optimal separation process only in that section of the chromatographic column through which the sample passes at an optional speed.
However the linear speed of the sample zone moving with the carrier-gas can be kept constant by programming the pressure gradient movement along the column in time, realizing the function: pressure - location - time by keeping constant the pressure difference ∆ p at the ends of the chromatographic column during the whole cycle of the analysis (Russia Patent "Chromatograph of A. S. Hayrapetyan").
For the first time in the world this basic technology was worked out and proposed, based on the investigation of the factors of diffusion and kinetics, and includes the meaning "bar-gradient chromatography" or Chromabarography, not included in the standard terminology for gas chromatography of the International Union of Theoretical and Applied Chemistry (IUTAC).
For the realization of the basic technology an equipment was invented and defended by a Russia patent. As a result a maximum possible efficiency (Hayrapetyan's Effect) of column is obtained at a minimum length, which at the same time is optimal as well, as in difference to the ordinary column a further increase in column length increases the analysis time.
These are not the only advantages of Chromabarography. On the contrary, interesting possibilities of its modification have been revealed, which envisage:
A combined application of the moving pressure gradient and temperature (Chromabarothermography)
Or the moving pressure gradient along the column in combination with temperature programming equally inflicted to the whole chromatographic column (Chromabarograph with temperature programming).

Looks like self promotion or hype for a dubious technology. Google search returns around 700 hits for the term, but a good number on the first pages appear to be hype written by the same person that wrote this - based on style and wording. Several were discussion on blogs or whatever signed by one ARAM HAYRAPETYAN, presumably the inventor of Chromabarography. Many Russian sites on the Google list. If it is real it is yet too new and unverified to include here. -Vsmith 02:03, 31 Jan 2005 (UTC)
Thanks for checking, I thought the same thing --nixie 02:24, 31 Jan 2005 (UTC)
I agree Cacycle 11:31, 31 Jan 2005 (UTC)

Very entertaining, indeed. Packed column supercritical fluid chromatography uses a pressure regulator at the column outlet keeping the pressure constant, should the user so desire, irrespective (within the design limitations of the equipment) of flowrate, mobile phase composition, and temperature. The body governing nomenclature conventions is the IUPAC, International Union of Pure and Applied Chemistry, http://www.iupac.org BTW, the original invention by Tswett (pick your transcription) held the column outlet at constant pressure: it was held at ambient pressure.

Paper chromatography[edit]

Correct me if I'm wrong, but I think that paper chromatography is really a very minor subject in modern chromatography. I don't think it should have such prominence in the article. I can understand how it is good as a demonstration of the principle. If it is actually used in any modern analytic procedures, these should be mentioned. ike9898

It's used a tiny bit for pigement seperation by some botanists, although TLC would be more commonly used for the same procedure. The paper chromotography section is quite well written, and does clearly explain the principle of chromotography, plus it is a technique that a high-school or undergrad student may come across, so I'd be hesitant to see it cut. Mabye we should add a sentence to say that it is no longer a procedure widely used in labs --nixie 23:28, 15 Feb 2005 (UTC)

As an encyclopedic topic, paper chromatography occupies a critical position in the historic development of the science of chromatography. I support nixie's contention about the quality and relevance of the section. If an edit is needed, it is the moving of the IMAC description to the affinity chromatography section and the drafting of an accurate ion exchange section, arguably one of the most important techniques in the modern chromatographic arsenal. :M Signs 16:49, 11 Mar 2005 (UTC)

Gas-liquid chromatography[edit]

I am I just being biased, or is this a rather cursory, and incorrect (GC is useful for both non-polar and polar compounds--it just depends on what column you use), comment on GC compared to the other sections? On the whole, this article seems to give a bio-researcher's POV of GC. Pi3832 15:34, 22 May 2006 (UTC)

Structure[edit]

Any objections to restructuring the article to make it more organised? It would look a little like this:

Chromatography

  • History
  • Chromatography theory
Retention
Plate theory
  • Solid-liquid chromatography
Affinity chromatography
Column chromatography
Ion exchange chromatography
High performance liquid chromatography
Normal phase (NP) liquid chromatography
Reversed phase (NP) liquid chromatography
Paper chromatography
Thin layer chromatography
Size exclusion chromatography
  • Liquid-liquid chromatography
Countercurrent chromatography
  • Gas-liquid chromatography


Or does anyone have any improvements? The whole array of chromatographic techniques on Wikipedia is jumbled and in need of some order -- Serephine talk - 14:05, 20 June 2006 (UTC)

Go for it.--Pi3832 16:05, 21 June 2006 (UTC)

I would add capillaryelectrochromatography since it has way more applications and importance in analytical chemistry than some of the applications already included. It would also be nice if there was a section or at least a link to microchip technologies since it happens to be the hottest thing around at the moment. Dv3 19:17, 16 April 2007 (UTC)

My Recent Edits[edit]

Here's the explanation of what I changed:

1. Saying that chromatography paper is "dipped" makes it sound like the paper is completely submerged in solvent. This would be disastrous.
2. TLC stationary phase is bonded to a substrate, not a carrier. The use of this word here could be confused with, e.g. carrier gas.
3. A substances retention time, Rf value, etc. is not definitive proof of its identity. Although it is very useful, spectroscopic methods are always used for further verification.
4. In GC, the stationary phase, whether in a capillary or packed column, is always solid. A liquid stationary phase would not stay stationary for very long, especially with a stream of gas flowing over it.
5. The entire TLC plate is not made out of silica, so I changed it to say "layer."

I hope you find my edits to be helpful. Mihovil 02:39, 19 September 2006 (UTC)

The physical state of the stationary phase, in the case of open tubular capillary, is actually more like liquid than solid. The layer is very thin and polymeric and it stays in the capillary because of the high surface tension and viscosity of the liquid. Dv3 19:24, 16 April 2007 (UTC)

Mikhail Semyonovich Tsvet[edit]

A user at IP address 66.71.48.70 has repeatedly changed the spelling of "Mikhail Semyonovich Tsvet". The alternate spelling is referenced at the article Mikhail Tsvet. The persistent revision of the spelling in this article seems to be bordering on vandalism. -- Pi3832 00:51, 28 February 2007 (UTC)

IP user 66.71.58.169 does it also. I concur that it's inappropriate. Can't figure out why we should be using anything other than the guy's own page's name and primary spelling when linking to his page and spelling his name. DMacks 02:26, 28 February 2007 (UTC)

clc[edit]

Someone just asked me about clc. I found this: http://www.polymicro.com/catalog/3_5.htm --Gbleem 05:05, 5 April 2007 (UTC)

Bees/wasps analogy[edit]

I just removed the following comment:

This is the copied form from colby Reynolds (NTI) paper of 2002

from the bees/wasps analogy because it's commentary not encyc content and it's not clear what it even means. If there's a copyright concern for this text, need a complete citation. Conversely, many organic and analytical profs and textbooks use at least one animal-behavior example for teaching chromatography and I've heard bees well before 2002, so I don't think referencing this work to cite the idea is valid. DMacks 18:12, 8 May 2007 (UTC)

I agree, what the hell is this business with starting a chemistry article with some sort of weird story about bees and wasps, this is original content or someones personal idea of chromatography. The explanation of chromatography is simple enough, you just explain what it does and move on. Its very unencyclopedic. —Preceding unsigned comment added by 66.76.60.163 (talk) 07:09, 13 October 2008 (UTC)

Borax[edit]

I just snipped this addition about borax from the Affinity Chromatography sub section:

You also should be sure to clean all suplies with borax before using, this way the solutions will with hold procedures in a more substansial way.

If it's correct, it might belong in the Affinity Chromatography page, but it's still a bit too technical for any encyclopedia article. Jmeppley 22:25, 26 September 2007 (UTC)



lizzy[edit]

when i was using the black marker i had 2 draw a thick line around the middle surface and the n i had 2 get a cup that was fulled with water and place the tip of the filter into the cup and i left it for about 20 minutes and then all the colors came out, yellow, blue, red, green, purple, and many other colors.Rainbow colors to exact. but i had some difficulty's, the first time that experiment and i put it into the water and left it for about 15 minutes or more it came out gray and black and it was a very faded colors. so i tried it again and then the colors came out and i am still wondering why that format was like that cause i was watching it the hole time and i thought that i was a little bit of color coming out remarkable. I couldn't believe that i had this project 2 do and like so many colors came out and i judged it by its colors. yes i know its not good to do that =). anyway my project was a sudses but all i need 2 do it show it to my class and get my grade. when i do ill get right back to you.discharge —Preceding unsigned comment added by 74.64.65.196 (talk) 15:41, 16 March 2008 (UTC)


Layman's question[edit]

Being an outsider I have to ask for confirmation from an expert: am I wrong in saying that the two groups of applications, a) preparative and b) analytical need different sequential treatment, that is to say that for the preparative purpose the column is chopped to bits for individual testing of its parts, and therefore the analytes stay in the column, whereas for the analytical purpose it is driven through with the solvent so that residence time of each component can be measured by the instruments? If this is the case, then the explanation for the solvent is incorrect. Further, it is not absolutely clear how many words are used for the static phase, and what is the name of the filling support of the static phase, or have I overlooked anything? LouisBB (talk) 05:01, 5 May 2008 (UTC)

Your understanding of the different applications is not correct. In all cases, either the distance the analyte moves or its residence time is measured to identify the analyte. For analytical purposes, one mainly cares about how much of each analyte is present; for preparative purposes, one mainly cares about recovering a certain analyte. For preparative purposes, cutting apart the column is the least useful thing, because the whole goal is to get the analyte itself, not just see where it is (which is an analytical issue). DMacks (talk) 05:09, 5 May 2008 (UTC)
Thankyou DMacks for the explanation. Unfortunately to me everything is still not quite clear. What do you mean by saying that the distance of the analyte moves, i.e. per unit time ? In the explanation of column chromatography it is clear that the comumn is not chopped up, but the introduction does not specify how the separate analytes are collected for further use. The definition of the solvent does not say that it is used for carrying the analytes through, rather than to dissolve the sample. Also not that different solvents might be used for carrying different types of compounds through. Is this understanding also incorrect in your view? Then it is still not clear why so many expressions with similar meanings are used under separate entries in the list of terms, static phase, stationary phase, immobilised phase, and what the actual support is called. I am reading the encyclopaedia because I want to learn, so I would like to see clear, compact, concise explanations in the article. Thanks again LouisBB (talk) 12:51, 6 May 2008 (UTC)

Monolithic columns[edit]

I am no longer in the business of running columns in the laboratory, so I do not feel qualified to insert the material I suggest here. I think that there should be some mention of so-called "monolithic column chromatography" as described, for instance, in

Gagnon, Pete (2008-8-01), "Monoliths Emerge as Key Purification Methodology", Genetic Engineering & Biotechnology News, Mary Ann Liebert, 28 (14), pp. 1, 48–50, ISSN 1935-472X, retrieved 2008-09-20  Check date values in: |date= (help)

Thanks for considering this. --User:Ceyockey (talk to me) 21:59, 20 September 2008 (UTC)

Rf info?[edit]

There is an equation that is called an Rf which tells how much of what part is in the substance. I think this should be mentioned. —Preceding unsigned comment added by 76.240.22.118 (talk)

Rf tells you something about the chemical, not how much. We actually have a whole page about just that value: Retardation factor. It's too specific for this already too long (IMO) and general-info page and only applies to some types of chromatography...check the pages about the specific type you're doing (TLC probably?). On the other hand, "Rf" is mentioned, so may as well link it. DMacks (talk) 21:40, 19 October 2008 (UTC)

data analysis[edit]

as someone who analyzes DNA by gels and Capillary electrophoresis, which is similar to LC, a big part of any chromatography or similr system is data analysis. Eg, the term resolution, which is roughly (diff in migration time)/sum of bandwidths*a factor, is a key concept, —Preceding unsigned comment added by 108.7.0.214 (talk) 17:37, 22 June 2010 (UTC)

Edit request from 194.249.198.32, 26 January 2011[edit]

{{edit semi-protected}}

Dear sir or madame, I miss a link from the original Chromatography article (http://en.wikipedia.org/wiki/Chromatography) in the section Liquid chromatography at text point: "... a porous monolithic layer (stationary phase) or ..." to the article regarding the same subject at http://en.wikipedia.org/wiki/Monolithic_HPLC_column. The field of monolith is very developed and is becoming a mainstream due to its high performance in comparison to other obsolete methods which are linked.

Thank you for your consideration


best regards Mario Simic

194.249.198.32 (talk) 15:48, 26 January 2011 (UTC)

 Done Thanks! DMacks (talk) 16:08, 26 January 2011 (UTC)

Edit request from 188.51.73.80, 14 February 2011[edit]

{{edit semi-protected}} Please add this to Pyrolysis gas chromatography: Pyrolysis gas chromatography mass spectrometry is a method of chemical analysis in which the sample is heated to decomposition to produce smaller molecules that are separated by gas chromatography and detected using mass spectrometry.[1]

Pyrolysis is the thermal decomposition of materials in an inert atmosphere or a vacuum. The sample is put into direct contact with a platinum wire, or placed in a quartz sample tube, and rapidly heated to 600 – 1000° C. Depending on the application even higher temperatures are used. Three different heating techniques are used in actual pyrolyzers: Isothermal furnace, inductive heating (Curie Point filament), and resistive heating using platinum filaments. Large molecules cleave at their weakest points and produce smaller, more volatile fragments. These fragments can be separated by gas chromatography. Pyrolysis GC chromatograms are typically complex because a wide range of different decomposition products is formed. The data can either be used as fingerprint to prove material identity or the GC/MS data is used to identify individual fragments to obtain structural information. To increase the volatility of polar fragments, various methylating reagents can be added to a sample before pyrolysis.

Besides the usage of dedicated pyrolyzers, pyrolysis GC of solid and liquid samples can be performed directly inside Programmable Temperature Vaporizer (PTV) injectors that provide quick heating (up to 30°C/sec) and high maximum temperatures of 600 - 650° C. This is sufficient for some pyrolysis applications. The main advantage is that no dedicated instrument has to be purchased and pyrolysis can be performed as part of routine GC analysis. In this case quartz GC inlet liners have to be used. Quantitative data can be acquired, and good results of derivatization inside the PTV injector are published as well.[2][3]

188.51.73.80 (talk) 13:51, 14 February 2011 (UTC)

Done I added it. But what are your sources? Without them in the article, the material will likely be removed. -Atmoz (talk) 16:01, 14 February 2011 (UTC)

Phase[edit]

I can tell the word "phase" is important, because it appears 74 times in the article. From the context, I gather it's a substance that is not itself being analyzed, but which the analyte interacts with. However, the term is never explicitly defined, not even in the very helpful section "Chromatography terms". Nor is there a definition in Phase that seems to fit. The chromatography article would benefit from a sentence or two. If I do it, someone will be horrified and have to fix it. Might be more efficient for a chemist to write it in the first place. Spiel496 (talk) 21:20, 19 February 2011 (UTC)

File:Dynamic 1-4.jpg Nominated for speedy Deletion[edit]

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Wrong redirect[edit]

The redirect (Adsorption chromatography) should be an article itself. It exists, for example, in German wiki: [1]--Bioneer1 (talk) 18:08, 28 November 2012 (UTC)

Liquid Chromatography Stationary Phase: Normal has "fewer applications"?[edit]

The article subsection on Liquid Chromatography makes the claim that normal (polar) stationary phases, typically silica or alumina, have fewer applications than the various types of non-polar functionalized stationary phases (usually alkane or aromatic functionalization). This is simply not true. Neither for HPLC, nor chromatography in general. Even if you fooled yourself into including more niche or specific applications like SEC (or even membranes)in this discussion, you would still find that the chemical/biochemical/materials/pharmaceutical industries still utilize a significantly larger amount of normal stationary phase material than reverse phase. EVEN IF you were to attempt to say "Ah ha! but RP is more expensive, so people don't dispose of it as quickly," you would still find that (even weighted for this fact), silica and alumina are used more widely and more commonly than RP.184.189.220.114 (talk) 07:12, 5 January 2013 (UTC)

I removed the statement from the article. WP:V is policy, and it's been several months without anyone supplying support for that claim you dispute. DMacks (talk) 11:21, 2 July 2013 (UTC)

Advance technique question[edit]

i want to know what is advance techique of chromatography can anyone help me throught this. — Preceding unsigned comment added by 14.99.17.56 (talk) 01:31, 2 July 2013‎ (UTC)


Question on the Details of Chromatography's Origin[edit]

Hi, I have a question and thought that since someone is working on this article currently, they may perhaps see it. This article implies that Mikhail Tsvet invented chromatography, and I accepted that without question (several other sites said similar things) until recently. But two things jump out now that I've done a little reading off Wikipedia. First of all, wasn't Tsvet's discovery actually 1903, as opposed to 1900? I would like for someone could verify this.

Second, was Tsvet really the first to use chromatography? ONE site, which I accessed today, gave a German chemist F.F. Runge credit for paper chromatography, which was obviously the first type developed, as early as 1867! The irony grew when I turned around and looked up Runge on Wikipedia and, sure enough, the original use of paper chromatography is attributed to him there also! Could someone already editing the page look into this, please? I'm thankful for the great resource Wikipedia is and would like to see it as accurate as possible. Thanks. 76.199.3.102 (talk) 00:00, 22 November 2013 (UTC) ItsARose -<@

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What drives chromatography?[edit]

The introduction and most of the sections about specific techniques reveal only that the mobile phase "carries" the mixture through the stationary phase, but never mention the driving force, which is a distinguishing property of various techniques. For example, the article merely says that in paper chromatography the solvent "rises". What causes that?

I suggest that driving force be recognized as a unifying theme that runs through the article, on a par with mobile and stationary phases. Unfortunately I don't have the expertise to do the job. Mdmi (talk) 15:33, 12 May 2017 (UTC)

Need fundamental overview[edit]

This page definitely needs some condensed fundamentals being described in terms of the physical essence of chromatography. Chromatography is first of all a physical method of separation of substances that is used NOT only for analytical purposes as the page gives the impression of, but also for industrial separation of substances, including not only chemically different substances, but different nuclear isotopes of the same chemical element (uranium 235 enrichment in the form of hexafluoride is a classic example where all other methods of separation are futile). In its extreme form chromatography separates substances according to the difference in masses of their molecules/atoms/ions, translating the latter into a difference of average velocities in a field of external (gravitational or some inertial) force. Heavier species under these conditions have a higher momentum and higher average speeds (not because they are accelerated more but because they are decelerated less by the stationary medium). Separation takes place because the heavier species get ahead and the lighter species lag behind. While there are different other things used by chromatography (like adsorption), it's extremely important to understand the above phenomenon because it is this that makes chromatography such a universal method that allows of separating not just elements but even different nuclei of the same element — Preceding unsigned comment added by Philipp Mirzoev (talkcontribs) 18:38, 9 July 2017 (UTC)

Our articles about UF6 and isotopic enrichment of it talk about gas centrifuges and gas diffusion, not chromatographic methods. Sounds like you are talking about a higher level sort of article, where "things separate based on different rates of motion", which includes diffusion, chromatography, distillation, sector mass spectrometers, etc. On the other hand (depending how I read your explanation), it would be reasonable to add the idea of collisional slowing (differentially due to initial inertia) or something like that as a "stationary phase" idea. DMacks (talk) 19:52, 9 July 2017 (UTC)